The present invention relates to the extraction of oil from wells and particularly to the use of ultrasonic energy to assist secondary recovery of oil from wells. It also pertains to the expedient passage of oil in pipelines and the separation of water from oil molecules containing water.
During the extraction of oil from a well, a time is reached at which the production from the well decreases to an uneconomically low value. This occurs because the quantity of oil remaining in the well is reduced, the remaining oil has a relatively high viscosity, and the pressure in the well has decreased to a low value.
In order to increase production of the remaining oil, or to perform "secondary recovery", various techniques have been proposed. One of these techniques involves exposure of the remaining oil to ultrasonic energy, which has been found to create a temporary reduction in the viscosity of the oil. In order to employ this technique on a practical level, it has been proposed to dispose an electroacoustic transducer element in the region of an oil producing formation of an oil well and to supply the transducer with alternating current at a suitable frequency. One such arrangement is disclosed in U.S. Pat. No. 3,322,196 which describes arrangements in which an oscillator and amplifier and associated electrical components for producing the electrical signal are disposed with the well in close proximity to the transducer element.
The reason for disposing the electrical components in proximity to the transducer element is to prevent unacceptably high electrical losses between the power generating components and the transducer itself.
In general, it is considered necessary to connect a power supply to an electroacoustic transducer element by a cable having a relatively short length. For example, a known device for reducing the viscosity of liquids in laboratory and industrial applications is specified to be usable with a cable having a length not exceeding 19 feet.
However, the use of such an arrangement in an oil well has been found to present a number of drawbacks. Thus, for example, all of the electrical components are relatively bulky so that difficulties are encountered in mounting these components for introduction into the well. Moreover, because of the high temperatures which exist within a well having any significant depth, various components of the electrical system will fail after a short period of time.
In the instance of dealing with oil in pipelines difficulties have been encountered in transporting the oil because of its thickness. To overcome this, additives or heat has been used or technology along the lines discussed above has been employed. If the viscosity is reduced in view of the above-noted technology the difficulties of locating and mounting the equipment is again encountered.
In the instance of separating oil from water, when the oil molecule is composed of water an elaborate system is used to separate the oil from this water. The oil is exposed to temperatures in the range of 600 to 1,000 degrees fahrenheit as it is fed into a separation tank which generally holds between 1,000 to 1,500 barrels. In some instances a solvent is also mixed into the oil. The water being heavier than the oil thereby separates and falls to the bottom of the tank. The oil is then siphoned off of the top of the tank for further use. The method is time consuming and uneconomical.